1. Field of the Invention
The present invention relates to an angular velocity sensor for detecting an angular velocity of an object and an angular velocity sensing device including the same.
2. Description of the Related Art
An angular velocity sensor using the Coriolis force is generally known as an element for detecting angular velocity of objects, (for example, refer to Japanese Patent Publications No. 2003-227719, 08-128833, 2004-333460, 2005-106481 and Japanese Patent No. 3694160). The Coriolis force is generated when a vibratile mass body (base portion) is rotated, and angular velocity is detectable by detecting a vibration generated due to the Coriolis force.
In angular velocity sensors, piezoelectric elements are generally used as a means to vibrate the base portion and detect the vibration thereof. The piezoelectric element typically has a laminated structure in which a piezoelectric crystal is sandwiched by a pair of electrodes. A pair of the piezoelectric elements are disposed in parallel on the surface of the base portion along a direction orthogonal to the expanding or contracting direction of the piezoelectric elements. With this arrangement, the base portion can be bent and vibrated in the arrangement direction by expanding one of the piezoelectric elements and contracting the other of the piezoelectric elements. When the base portion is bent due to the Coriolis force, a voltage is generated in the piezoelectric elements due to the bending, thus angular velocity for objects can be detected by measuring a detection signal obtained from the voltage (refer to Japanese Patent Publication No. 2003-227719).